public class HashBuch2<K,V> {

    static class Node<K,V>{
        public K key;
        public V val;
        public Node<K,V> next;

        public Node (K key, V val){
            this.key = key;
            this.val = val;
        }
    }

    public Node<K,V>[] array = (Node<K, V>[]) new Node[10];
    public int usedSize;

    public static final double DEFAULT_LOAD_FACTOR = 0.75f;

    public void push(K key,V val){
        int hashcode = key.hashCode();//将字符类型转化为数字类型，才能进行比较
        int index = hashcode % array.length;
        Node<K,V> cur = array[index];
        while (cur!= null){
            if (cur.key.equals(key)){
                cur.val =val;
                return;
            }
            cur = cur.next;
        }
        Node<K,V> node = new Node<>(key,val);
        node.next = array[index];
        array[index] =node;
        usedSize++;
        if(doLoadFactor() >= DEFAULT_LOAD_FACTOR) {
            resize(key);
        }
    }

    private void resize(K key) {
        //array = Arrays.copyOf(array,2*array.length);

        Node<K,V>[] newArray = (Node<K, V>[]) new Node[2*array.length];

        for (int i = 0; i < array.length; i++) {
            Node cur = array[i];
            while (cur != null) {
                int hashcode = key.hashCode();
                int newIndex = hashcode % newArray.length;
                Node curN = cur.next;
                cur.next = newArray[newIndex];
                newArray[newIndex] = cur;
                cur = curN;
            }
        }
        array = newArray;
    }

    private double doLoadFactor() {
        return usedSize*1.0 / array.length;
    }

    public V getVal(K key) {
        int hashcode = key.hashCode();
        int index = hashcode % array.length;
        Node<K,V> cur = array[index];
        while (cur != null) {
            if(cur.key.equals(key)) {
                return cur.val;
            }
            cur = cur.next;
        }
        return null;
    }
}
